In electronic components (devices) such as solar cell panels, plasma display panels (PDPs) and liquid crystal display (LCD) panels, an electrode/wiring member (interconnection member) is formed on the approximately entire surface of the panel. Such an interconnection member is formed by applying, on a substrate (such as silicon and glass substrates), an electrically conductive paste containing a metal powder, a glass powder, a resin binder and a solvent, and firing the applied paste. The conductive paste is heated above the softening point of the glass powder contained in the paste, and as a result the glass powder softens and flows. By this firing process, the interconnection member becomes formed of a dense material and also strongly adheres to the substrate.
For example, in solar cell panels, a light receiving plane interconnection member is formed on the light receiving plane of the solar cell, and a current collecting interconnection member and an output interconnection member are formed on the back side plane of the cell. Typically, silver is used for the light receiving plane interconnection member and the output interconnection member, and aluminum is used for the current collecting interconnection member. A problem is that conventionally, these interconnection members also contain a lead-containing glass composition.
In these years, with the worldwide strong trend towards environmentalism, the use of environmentally hazardous materials such as lead and mercury is increasingly restricted. Europe enforces “DIRECTIVE 2002/95/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 27 Jan. 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment” (the RoHS directive adopted by the European Union). To comply with the RoHS directive, various lead-free glass compositions for interconnection member use are being proposed. For example, Patent Literature 1 (JP-A 2008-543080, WO2006/132766) and Patent Literature 2 (JP-A 2007-59380) disclose a glass composition containing bismuth oxide as a major constituent. Patent Literature 3 (JP-A Hei 7 (1995)-69672) discloses a glass composition containing tin oxide as a major constituent. Patent Literature 4 (JP-A 2004-250276) discloses a glass composition containing vanadium oxide as a major constituent.    Patent Literature 1: Japanese Patent Laid-open No. 2008-543080    Patent Literature 2: Japanese Patent Laid-open No. 2007-59380    Patent Literature 3: Japanese Patent Laid-open No. Hei 7 (1995)-69672    Patent Literature 4: Japanese Patent Laid-open No. 2004-250276